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Commit 2385d330 authored by Srivatsa Vaddagiri's avatar Srivatsa Vaddagiri
Browse files

sched: Support CFS_BANDWIDTH feature in HMP scheduler 



CFS_BANDWIDTH feature is not currently well-supported by HMP
scheduler. Issues encountered include a kernel panic when
rq->nr_big_tasks count becomes negative. This patch fixes HMP
scheduler code to better handle CFS_BANDWIDTH feature. The most
prominent change introduced is maintenance of HMP stats (nr_big_tasks,
nr_small_tasks, cumulative_runnable_avg) per 'struct cfs_rq' in
addition to being maintained in each 'struct rq'. This allows HMP
stats to be updated easily when a group is throttled on a cpu.

Change-Id: Iad9f378b79ab5d9d76f86d1775913cc1941e266a
Signed-off-by: default avatarSrivatsa Vaddagiri <vatsa@codeaurora.org>
parent bbef4c5e

kernel/sched/core.c

+3 −2
Original line number Diff line number Diff line
@@ -2066,8 +2066,9 @@ void reset_all_window_stats(u64 window_start, unsigned int window_size) 
#ifdef CONFIG_SCHED_FREQ_INPUT

		rq->curr_runnable_sum = rq->prev_runnable_sum = 0;

#endif

		rq->hmp_stats.cumulative_runnable_avg = 0;

		fixup_nr_big_small_task(cpu);

		reset_cpu_hmp_stats(cpu, 1);



		fixup_nr_big_small_task(cpu, 0);

	}



	if (sched_window_stats_policy != sysctl_sched_window_stats_policy) {

kernel/sched/debug.c

+12 −0
Original line number Diff line number Diff line
@@ -231,6 +231,16 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq) 
			cfs_rq->throttled);

	SEQ_printf(m, "  .%-30s: %d\n", "throttle_count",

			cfs_rq->throttle_count);

	SEQ_printf(m, "  .%-30s: %d\n", "runtime_enabled",

			cfs_rq->runtime_enabled);

#ifdef CONFIG_SCHED_HMP

	SEQ_printf(m, "  .%-30s: %d\n", "nr_big_tasks",

			cfs_rq->hmp_stats.nr_big_tasks);

	SEQ_printf(m, "  .%-30s: %d\n", "nr_small_tasks",

			cfs_rq->hmp_stats.nr_small_tasks);

	SEQ_printf(m, "  .%-30s: %llu\n", "cumulative_runnable_avg",

			cfs_rq->hmp_stats.cumulative_runnable_avg);

#endif

#endif



	print_cfs_group_stats(m, cpu, cfs_rq->tg);
@@ -318,6 +328,8 @@ do { \ 
#ifdef CONFIG_SCHED_HMP

	P(hmp_stats.nr_big_tasks);

	P(hmp_stats.nr_small_tasks);

	SEQ_printf(m, "  .%-30s: %llu\n", "hmp_stats.cumulative_runnable_avg",

			rq->hmp_stats.cumulative_runnable_avg);

#endif

#undef P

#undef PN

kernel/sched/fair.c

+318 −37
Original line number Diff line number Diff line
@@ -2186,31 +2186,195 @@ dec_nr_big_small_task(struct hmp_sched_stats *stats, struct task_struct *p) 
	BUG_ON(stats->nr_big_tasks < 0 || stats->nr_small_tasks < 0);

}



static void inc_rq_hmp_stats(struct rq *rq, struct task_struct *p)

static void

inc_rq_hmp_stats(struct rq *rq, struct task_struct *p, int change_cra)

{

	inc_cumulative_runnable_avg(&rq->hmp_stats, p);

	inc_nr_big_small_task(&rq->hmp_stats, p);

	if (change_cra)

		inc_cumulative_runnable_avg(&rq->hmp_stats, p);

}



static void dec_rq_hmp_stats(struct rq *rq, struct task_struct *p)

static void

dec_rq_hmp_stats(struct rq *rq, struct task_struct *p, int change_cra)

{

	dec_nr_big_small_task(&rq->hmp_stats, p);

	if (change_cra)

		dec_cumulative_runnable_avg(&rq->hmp_stats, p);

}



static void reset_hmp_stats(struct hmp_sched_stats *stats, int reset_cra)

{

	stats->nr_big_tasks = stats->nr_small_tasks = 0;

	if (reset_cra)

		stats->cumulative_runnable_avg = 0;

}





#ifdef CONFIG_CFS_BANDWIDTH



static inline struct task_group *next_task_group(struct task_group *tg)

{

	tg = list_entry_rcu(tg->list.next, typeof(struct task_group), list);



	return (&tg->list == &task_groups) ? NULL : tg;

}



/* Iterate over all cfs_rq in a cpu */

#define for_each_cfs_rq(cfs_rq, tg, cpu)	\

	for (tg = container_of(&task_groups, struct task_group, list);	\

		((tg = next_task_group(tg)) && (cfs_rq = tg->cfs_rq[cpu]));)



static void reset_cfs_rq_hmp_stats(int cpu, int reset_cra)

{

	struct task_group *tg;

	struct cfs_rq *cfs_rq;



	rcu_read_lock();



	for_each_cfs_rq(cfs_rq, tg, cpu)

		reset_hmp_stats(&cfs_rq->hmp_stats, reset_cra);



	rcu_read_unlock();

}



#else	/* CONFIG_CFS_BANDWIDTH */



static inline void reset_cfs_rq_hmp_stats(int cpu, int reset_cra) { }



#endif	/* CONFIG_CFS_BANDWIDTH */



/*

 * reset_cpu_hmp_stats - reset HMP stats for a cpu

 *	nr_big_tasks, nr_small_tasks

 *	cumulative_runnable_avg (iff reset_cra is true)

 */

void reset_cpu_hmp_stats(int cpu, int reset_cra)

{

	reset_cfs_rq_hmp_stats(cpu, reset_cra);

	reset_hmp_stats(&cpu_rq(cpu)->hmp_stats, reset_cra);

}



#ifdef CONFIG_CFS_BANDWIDTH



static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq);



static void inc_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq,

	 struct task_struct *p, int change_cra);

static void dec_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq,

	 struct task_struct *p, int change_cra);



/* Add task's contribution to a cpu' HMP statistics */

static void

_inc_hmp_sched_stats_fair(struct rq *rq, struct task_struct *p, int change_cra)

{

	struct cfs_rq *cfs_rq;

	struct sched_entity *se = &p->se;



	/*

	 * Although below check is not strictly required  (as

	 * inc/dec_nr_big_small_task and inc/dec_cumulative_runnable_avg called

	 * from inc_cfs_rq_hmp_stats() have similar checks), we gain a bit on

	 * efficiency by short-circuiting for_each_sched_entity() loop when

	 * !sched_enable_hmp || sched_disable_window_stats

	 */

	if (!sched_enable_hmp || sched_disable_window_stats)

		return;



	for_each_sched_entity(se) {

		cfs_rq = cfs_rq_of(se);

		inc_cfs_rq_hmp_stats(cfs_rq, p, change_cra);

		if (cfs_rq_throttled(cfs_rq))

			break;

	}



	/* Update rq->hmp_stats only if we didn't find any throttled cfs_rq */

	if (!se)

		inc_rq_hmp_stats(rq, p, change_cra);

}



/* Remove task's contribution from a cpu' HMP statistics */

static void

_dec_hmp_sched_stats_fair(struct rq *rq, struct task_struct *p, int change_cra)

{

	struct cfs_rq *cfs_rq;

	struct sched_entity *se = &p->se;



	/* See comment on efficiency in _inc_hmp_sched_stats_fair */

	if (!sched_enable_hmp || sched_disable_window_stats)

		return;



	for_each_sched_entity(se) {

		cfs_rq = cfs_rq_of(se);

		dec_cfs_rq_hmp_stats(cfs_rq, p, change_cra);

		if (cfs_rq_throttled(cfs_rq))

			break;

	}



	/* Update rq->hmp_stats only if we didn't find any throttled cfs_rq */

	if (!se)

		dec_rq_hmp_stats(rq, p, change_cra);

}



static void inc_hmp_sched_stats_fair(struct rq *rq, struct task_struct *p)

{

	_inc_hmp_sched_stats_fair(rq, p, 1);

}



static void dec_hmp_sched_stats_fair(struct rq *rq, struct task_struct *p)

{

	_dec_hmp_sched_stats_fair(rq, p, 1);

}



static int task_will_be_throttled(struct task_struct *p);



#else	/* CONFIG_CFS_BANDWIDTH */



static void

inc_hmp_sched_stats_fair(struct rq *rq, struct task_struct *p)

{

	inc_nr_big_small_task(&rq->hmp_stats, p);

	inc_cumulative_runnable_avg(&rq->hmp_stats, p);

}



static void

dec_hmp_sched_stats_fair(struct rq *rq, struct task_struct *p)

{

	dec_nr_big_small_task(&rq->hmp_stats, p);

	dec_cumulative_runnable_avg(&rq->hmp_stats, p);

}



static inline int task_will_be_throttled(struct task_struct *p)

{

	return 0;

}



static void

_inc_hmp_sched_stats_fair(struct rq *rq, struct task_struct *p, int change_cra)

{

	inc_nr_big_small_task(&rq->hmp_stats, p);

}



#endif	/* CONFIG_CFS_BANDWIDTH */



/*

 * Walk runqueue of cpu and re-initialize 'nr_big_tasks' and 'nr_small_tasks'

 * counters.

 */

void fixup_nr_big_small_task(int cpu)

void fixup_nr_big_small_task(int cpu, int reset_stats)

{

	struct rq *rq = cpu_rq(cpu);

	struct task_struct *p;



	rq->hmp_stats.nr_big_tasks = 0;

	rq->hmp_stats.nr_small_tasks = 0;

	/* fixup_nr_big_small_task() is called from two functions. In one of

	 * them stats are already reset, don't waste time resetting them again

	 */

	if (reset_stats) {

		/* Do not reset cumulative_runnable_avg */

		reset_cpu_hmp_stats(cpu, 0);

	}



	list_for_each_entry(p, &rq->cfs_tasks, se.group_node)

		inc_nr_big_small_task(&rq->hmp_stats, p);

		_inc_hmp_sched_stats_fair(rq, p, 0);

}



/* Disable interrupts and grab runqueue lock of all cpus listed in @cpus */
@@ -2234,7 +2398,7 @@ void post_big_small_task_count_change(const struct cpumask *cpus) 


	/* Assumes local_irq_disable() keeps online cpumap stable */

	for_each_cpu(i, cpus)

		fixup_nr_big_small_task(i);

		fixup_nr_big_small_task(i, 1);



	for_each_cpu(i, cpus)

		raw_spin_unlock(&cpu_rq(i)->lock);
@@ -2464,6 +2628,10 @@ static inline int migration_needed(struct rq *rq, struct task_struct *p) 
	if (!sched_enable_hmp || p->state != TASK_RUNNING)

		return 0;



	/* No need to migrate task that is about to be throttled */

	if (task_will_be_throttled(p))

		return 0;



	if (sched_boost()) {

		if (rq->capacity != max_capacity)

			return MOVE_TO_BIG_CPU;
@@ -2577,20 +2745,6 @@ unsigned int cpu_temp(int cpu) 
		return 0;

}



static void

inc_hmp_sched_stats_fair(struct rq *rq, struct task_struct *p)

{

	inc_cumulative_runnable_avg(&rq->hmp_stats, p);

	inc_nr_big_small_task(&rq->hmp_stats, p);

}



static void

dec_hmp_sched_stats_fair(struct rq *rq, struct task_struct *p)

{

	dec_cumulative_runnable_avg(&rq->hmp_stats, p);

	dec_nr_big_small_task(&rq->hmp_stats, p);

}



#else	/* CONFIG_SCHED_HMP */



#define sysctl_sched_enable_power_aware 0
@@ -2662,18 +2816,16 @@ unsigned int cpu_temp(int cpu) 
	return 0;

}



static inline void inc_rq_hmp_stats(struct rq *rq, struct task_struct *p) { }

static inline void dec_rq_hmp_stats(struct rq *rq, struct task_struct *p) { }

static inline void

inc_rq_hmp_stats(struct rq *rq, struct task_struct *p, int change_cra) { }

static inline void

dec_rq_hmp_stats(struct rq *rq, struct task_struct *p, int change_cra) { }



static inline void

inc_hmp_sched_stats_fair(struct rq *rq, struct task_struct *p)

{

}

inc_hmp_sched_stats_fair(struct rq *rq, struct task_struct *p) { }



static inline void

dec_hmp_sched_stats_fair(struct rq *rq, struct task_struct *p)

{

}

dec_hmp_sched_stats_fair(struct rq *rq, struct task_struct *p) { }



#endif	/* CONFIG_SCHED_HMP */
@@ -3142,8 +3294,10 @@ static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq, 
static inline void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq,

					      int force_update) {}



static inline void inc_rq_hmp_stats(struct rq *rq, struct task_struct *p) { }

static inline void dec_rq_hmp_stats(struct rq *rq, struct task_struct *p) { }

static inline void

inc_rq_hmp_stats(struct rq *rq, struct task_struct *p, int change_cra) { }

static inline void

dec_rq_hmp_stats(struct rq *rq, struct task_struct *p, int change_cra) { }



#endif
@@ -3197,6 +3351,62 @@ static inline void decay_scaled_stat(struct sched_avg *sa, u64 periods) 
			   periods);

}



#ifdef CONFIG_CFS_BANDWIDTH



static void init_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq)

{

	cfs_rq->hmp_stats.nr_big_tasks = 0;

	cfs_rq->hmp_stats.nr_small_tasks = 0;

	cfs_rq->hmp_stats.cumulative_runnable_avg = 0;

}



static void inc_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq,

		 struct task_struct *p, int change_cra)

{

	inc_nr_big_small_task(&cfs_rq->hmp_stats, p);

	if (change_cra)

		inc_cumulative_runnable_avg(&cfs_rq->hmp_stats, p);

}



static void dec_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq,

		 struct task_struct *p, int change_cra)

{

	dec_nr_big_small_task(&cfs_rq->hmp_stats, p);

	if (change_cra)

		dec_cumulative_runnable_avg(&cfs_rq->hmp_stats, p);

}



static void inc_throttled_cfs_rq_hmp_stats(struct hmp_sched_stats *stats,

			 struct cfs_rq *cfs_rq)

{

	stats->nr_big_tasks += cfs_rq->hmp_stats.nr_big_tasks;

	stats->nr_small_tasks += cfs_rq->hmp_stats.nr_small_tasks;

	stats->cumulative_runnable_avg +=

				cfs_rq->hmp_stats.cumulative_runnable_avg;

}



static void dec_throttled_cfs_rq_hmp_stats(struct hmp_sched_stats *stats,

				 struct cfs_rq *cfs_rq)

{

	stats->nr_big_tasks -= cfs_rq->hmp_stats.nr_big_tasks;

	stats->nr_small_tasks -= cfs_rq->hmp_stats.nr_small_tasks;

	stats->cumulative_runnable_avg -=

				cfs_rq->hmp_stats.cumulative_runnable_avg;



	BUG_ON(stats->nr_big_tasks < 0 || stats->nr_small_tasks < 0 ||

		(s64)stats->cumulative_runnable_avg < 0);

}



#else	/* CONFIG_CFS_BANDWIDTH */



static inline void inc_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq,

	 struct task_struct *p, int change_cra) { }



static inline void dec_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq,

	 struct task_struct *p, int change_cra) { }



#endif	/* CONFIG_CFS_BANDWIDTH */



#else  /* CONFIG_SCHED_HMP */



static inline void
@@ -3208,6 +3418,24 @@ static inline void decay_scaled_stat(struct sched_avg *sa, u64 periods) 
{

}



static inline void init_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq) { }



static inline void inc_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq,

	 struct task_struct *p, int change_cra) { }



static inline void dec_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq,

	 struct task_struct *p, int change_cra) { }



static inline void inc_throttled_cfs_rq_hmp_stats(struct hmp_sched_stats *stats,

			 struct cfs_rq *cfs_rq)

{

}



static inline void dec_throttled_cfs_rq_hmp_stats(struct hmp_sched_stats *stats,

			 struct cfs_rq *cfs_rq)

{

}



#endif /* CONFIG_SCHED_HMP */



static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
@@ -3812,6 +4040,33 @@ static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) 
	return cfs_bandwidth_used() && cfs_rq->throttled;

}



/*

 * Check if task is part of a hierarchy where some cfs_rq does not have any

 * runtime left.

 *

 * We can't rely on throttled_hierarchy() to do this test, as

 * cfs_rq->throttle_count will not be updated yet when this function is called

 * from scheduler_tick()

 */

static int task_will_be_throttled(struct task_struct *p)

{

	struct sched_entity *se = &p->se;

	struct cfs_rq *cfs_rq;



	if (!cfs_bandwidth_used())

		return 0;



	for_each_sched_entity(se) {

		cfs_rq = cfs_rq_of(se);

		if (!cfs_rq->runtime_enabled)

			continue;

		if (cfs_rq->runtime_remaining <= 0)

			return 1;

	}



	return 0;

}



/* check whether cfs_rq, or any parent, is throttled */

static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)

{
@@ -3890,13 +4145,16 @@ static void throttle_cfs_rq(struct cfs_rq *cfs_rq) 
		if (dequeue)

			dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);

		qcfs_rq->h_nr_running -= task_delta;

		dec_throttled_cfs_rq_hmp_stats(&qcfs_rq->hmp_stats, cfs_rq);



		if (qcfs_rq->load.weight)

			dequeue = 0;

	}



	if (!se)

	if (!se) {

		rq->nr_running -= task_delta;

		dec_throttled_cfs_rq_hmp_stats(&rq->hmp_stats, cfs_rq);

	}



	cfs_rq->throttled = 1;

	cfs_rq->throttled_clock = rq->clock;
@@ -3905,6 +4163,13 @@ static void throttle_cfs_rq(struct cfs_rq *cfs_rq) 
	if (!cfs_b->timer_active)

		__start_cfs_bandwidth(cfs_b);

	raw_spin_unlock(&cfs_b->lock);



	/* Log effect on hmp stats after throttling */

	trace_sched_cpu_load(rq, idle_cpu(cpu_of(rq)),

			     mostly_idle_cpu(cpu_of(rq)),

			     sched_irqload(cpu_of(rq)),

			     power_cost_at_freq(cpu_of(rq), 0),

			     cpu_temp(cpu_of(rq)));

}



void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
@@ -3914,6 +4179,7 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq) 
	struct sched_entity *se;

	int enqueue = 1;

	long task_delta;

	struct cfs_rq *tcfs_rq = cfs_rq;



	se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
@@ -3939,17 +4205,27 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq) 
		if (enqueue)

			enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP);

		cfs_rq->h_nr_running += task_delta;

		inc_throttled_cfs_rq_hmp_stats(&cfs_rq->hmp_stats, tcfs_rq);



		if (cfs_rq_throttled(cfs_rq))

			break;

	}



	if (!se)

	if (!se) {

		rq->nr_running += task_delta;

		inc_throttled_cfs_rq_hmp_stats(&rq->hmp_stats, tcfs_rq);

	}



	/* determine whether we need to wake up potentially idle cpu */

	if (rq->curr == rq->idle && rq->cfs.nr_running)

		resched_task(rq->curr);



	/* Log effect on hmp stats after un-throttling */

	trace_sched_cpu_load(rq, idle_cpu(cpu_of(rq)),

			     mostly_idle_cpu(cpu_of(rq)),

			     sched_irqload(cpu_of(rq)),

			     power_cost_at_freq(cpu_of(rq), 0),

			     cpu_temp(cpu_of(rq)));

}



static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b,
@@ -4283,6 +4559,7 @@ static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) 
{

	cfs_rq->runtime_enabled = 0;

	INIT_LIST_HEAD(&cfs_rq->throttled_list);

	init_cfs_rq_hmp_stats(cfs_rq);

}



/* requires cfs_b->lock, may release to reprogram timer */
@@ -4462,6 +4739,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) 
		if (cfs_rq_throttled(cfs_rq))

			break;

		cfs_rq->h_nr_running++;

		inc_cfs_rq_hmp_stats(cfs_rq, p, 1);



		flags = ENQUEUE_WAKEUP;

	}
@@ -4469,6 +4747,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) 
	for_each_sched_entity(se) {

		cfs_rq = cfs_rq_of(se);

		cfs_rq->h_nr_running++;

		inc_cfs_rq_hmp_stats(cfs_rq, p, 1);



		if (cfs_rq_throttled(cfs_rq))

			break;
@@ -4480,7 +4759,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) 
	if (!se) {

		update_rq_runnable_avg(rq, rq->nr_running);

		inc_nr_running(rq);

		inc_rq_hmp_stats(rq, p);

		inc_rq_hmp_stats(rq, p, 1);

	}

	hrtick_update(rq);

}
@@ -4511,6 +4790,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) 
		if (cfs_rq_throttled(cfs_rq))

			break;

		cfs_rq->h_nr_running--;

		dec_cfs_rq_hmp_stats(cfs_rq, p, 1);



		/* Don't dequeue parent if it has other entities besides us */

		if (cfs_rq->load.weight) {
@@ -4531,6 +4811,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) 
	for_each_sched_entity(se) {

		cfs_rq = cfs_rq_of(se);

		cfs_rq->h_nr_running--;

		dec_cfs_rq_hmp_stats(cfs_rq, p, 1);



		if (cfs_rq_throttled(cfs_rq))

			break;
@@ -4542,7 +4823,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) 
	if (!se) {

		dec_nr_running(rq);

		update_rq_runnable_avg(rq, 1);

		dec_rq_hmp_stats(rq, p);

		dec_rq_hmp_stats(rq, p, 1);

	}

	hrtick_update(rq);

}

kernel/sched/sched.h

+7 −1
Original line number Diff line number Diff line
@@ -322,6 +322,11 @@ struct cfs_rq { 
	struct task_group *tg;	/* group that "owns" this runqueue */



#ifdef CONFIG_CFS_BANDWIDTH



#ifdef CONFIG_SCHED_HMP

	struct hmp_sched_stats hmp_stats;

#endif



	int runtime_enabled;

	u64 runtime_expires;

	s64 runtime_remaining;
@@ -737,7 +742,8 @@ extern unsigned int sched_init_task_load_pelt; 
extern unsigned int sched_init_task_load_windows;

extern unsigned int sched_heavy_task;



extern void fixup_nr_big_small_task(int cpu);

extern void reset_cpu_hmp_stats(int cpu, int reset_cra);

extern void fixup_nr_big_small_task(int cpu, int reset_stats);

u64 scale_load_to_cpu(u64 load, int cpu);

unsigned int max_task_load(void);

extern void sched_account_irqtime(int cpu, struct task_struct *curr,